The present invention generally relates to an integrated power and cooling machine and, more specifically, to an integrated power and cooling machine having indirect regenerative air cooling wherein the conditioned supply source may be isolated from the machine lubricating and heat transport fluid.
Prior art integrated power and cooling machines have at least two major design deficiencies. First, in using conventional machines, there may be leakage of operating fluid, lube oil and poly-alpha-olefin (PAO) coolant into the supply air, allowing these health-hazardous contaminants to migrate to, for example, passengers on an aircraft. Second, the operation of conventional integrated power and cooling machines requires excessive energy, such as excessive bleed air usage from the engine, which may penalize aircraft range and performance.
U.S. Pat. No. 5,442,905 to Claeys et al. discloses a closed loop thermodynamic cycle for a thermal and power management machine which is powered by preconditioned bleed air expanding in a turbine. The energy extracted from the air expansion in the power turbine is used to power the closed loop which comprises a compressor and another turbine. The closed loop serves as the main cooling source for the heat load of a compartment. The expanded bleed air at low temperature is then used to provide a fresh air source and supplemental cooling for compartment. The use of bleed air penalizes the engine performance and in turn causes a reduction in aircraft range.
U.S. Pat. No. 5,490,645 to Woodhouse discloses a fully integrated environmental and secondary power system that the system operates in combustion mode full time to raise the ambient air pressure to meet the cooling and pressurization demand of a pressurized compartment. The machine can also provide power to start aircraft main engine through a start/generator. Although the Woodhouse concept eliminates the demand of engine bleed air, the direct contact of the supply air flow path with the working fluid of the machine poses an undesirable health-hazardous contamination to a human occupied compartment.
U.S. Pat. No. 6,283,410 to Thompson describes a secondary power integrated cabin energy system for a pressurized aircraft. The system of Thompson couples an auxiliary power unit (APU) and an environmental control system (ECS) to produce cooling and power for aircraft usage. Cabin exhaust air is the main air source for combustion to produce power to operate the entire machine. Cabin air flow is supplied by the load compressor of the APU and fed to the ECS for final air conditioning. Similar to Woodhouse, the Thompson system eliminates bleed air demand from the aircraft, but fails to address the potential contamination of supply air.
As can be seen, there is a need for an improved integrated power and cooling machine having an indirect regenerative air cycle with low penalty bleed air source. Furthermore, there is a need for an improved method for supplying a conditioned supply air to an aircraft that is free of contaminants that may result from leakage of operating fluid.